But this is not the promissed merging neutron stars. It´s "only" from merging black holes of 21 and 35 SM but 40% more distant than GW150914, the first event. So this type of midd class BH seems to be much more often than foreseen by theory.

But this is not the promissed merging neutron stars. It´s "only" from merging black holes of 21 and 35 SM but 40% more distant than GW150914, the first event. So this type of midd class BH seems to be much more often than foreseen by theory.

I believe this post from the Universe project addresses that issue. It appears that the author predicted the prevalence of black hole mergers in the paper from 2010.